title: Methylphenidate does not improve interference control during a working memory task in young patients with attention-deficit hyperactivity disorder.
abstract: Patients with attention-deficit/hyperactivity disorder (ADHD) show deficits in working memory (WM) which may be related to prefrontal dysfunction. Methylphenidate (MPH) can restore WM deficits in ADHD by enhancing prefrontal activity. At the same time, changes in striatal activation could cause ADHD patients to be more interference-sensitive during working memory tasks. However, it is unclear whether MPH reduces WM distractibility in ADHD. In this fMRI study, 12 ADHD patients and 12 healthy controls participated on two separate days in a delayed-match-to-sample test. During the delay interval, a distractor stimulus was presented in half of the trials. Children and adolescents with ADHD received MPH only on one of the two sessions. Behavioral data analyses revealed that MPH normalized WM in ADHD. However, MPH did not improve WM performance when a distractor was presented during the delay interval. Functional images showed that MPH enhanced prefrontal activity during the delay in ADHD patients when no distractor was present. If the delay was interrupted by a distractor, only healthy controls showed activation of the caudate. In patients with ADHD, however, in line with behavioral data, MPH did not enhance caudate activity. In healthy youth, caudate activity is involved in interference control allowing the successful maintenance of information in working memory even in the presence of distraction. Our findings suggest that interference control, linked to caudate activity, is not adequately enhanced by MPH in ADHD.
authors.affiliation: Department of Child and Adolescent Psychiatry and Psychotherapy, Niemannsweg 147, Center for Integrative Psychiatry, 24105 Kiel, Germany. a.prehn@zip-kiel.de
authors.forename: Alexander
authors.initials: A
authors.lastname: Prehn-Kristensen
authors.forename: Kerstin
authors.initials: K
authors.lastname: Krauel
authors.forename: Hermann
authors.initials: H
authors.lastname: Hinrichs
authors.forename: Jochen
authors.initials: J
authors.lastname: Fischer
authors.forename: Ulrike
authors.initials: U
authors.lastname: Malecki
authors.forename: Hartmut
authors.initials: H
authors.lastname: Schuetze
authors.forename: Stephan
authors.initials: S
authors.lastname: Wolff
authors.forename: Olav
authors.initials: O
authors.lastname: Jansen
authors.forename: Emrah
authors.initials: E
authors.lastname: Duezel
authors.forename: Lioba
authors.initials: L
authors.lastname: Baving
mesh_terms: D000293:Adolescent; D001288:Attention / Q000187:drug effects*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy* / Q000503:physiopathology; D001921:Brain / Q000187:drug effects*; D001931:Brain Mapping; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects*; D008774:Methylphenidate / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate